Controller for electric motors.



T. s PERKINS. UONTRQLLER FOR ELECTRIC MOTORS. APPLICATION FILED MAR. 7,1904. 914,972, Patented Mar. 9, 1909.

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T. S. PERKINS. CONTROLLER FOR ELECTRIC MOTORS.

APPLICATION FILED MARJ, 1904.

Pate nted Mar. 9, 1909.

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WITNESSES Q T. S. PERKINS.

CONTROLLER FOR ELEGTRIG MOTORS.

APPLICATION FILED MAR. 7, 1904.

Patented Mar. 9, 1909.

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40 ing viewon line III-' III' of UNITED STATES PATENT 1 OFFICE,

THOMAS S. PERKINS, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TOWESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OFPENNSYLVANIA.

CONTROLLER FOR ELECTRIC MOTORS.

Applidation filed March 7,

v i Specification of Letters Patent.

Patented March 9, 1909. v 1904. Serial No. 196,949.

To all 'whom it may concern:

- Be it known thatI, THOMAS S. PERKINS, a citizen of the United States,and a resident of Wilkinsburg, in the county of Allegheny andState ofPennsylvania, have invented a new and useful Improvement in Controllersfor Electric Motors, of which the following is a specification.

My invention relates to controllers for electric motors, and it has forits object to rovide means for preventing injurious spar 'ng andflashing at the brushes of electric motors when starting and whenoperating temporarily as generators.

In the operation of shunt and compound Wound, variable speed motors, inwhich the speed variation is obtained by the successive application oftwo or more voltages and by varyi the current in the shunt winding ofthe fie d magnet, or by either of these expedicnts alone, it has beenfound that, when changing, the motor connections from a higher to alower voltage, or when suddenly strengthening the motor field, serioussparking occurs at the commutator brushes by reason of the fact that themotor temporarily" acts asa generator-and delivers current'to the supplycircuit.

' Mymventiomprovides simple mechanical means for inserting a resistanceinto the I110 tor' armature circuit during a predetermined period oftimewhen the motor is started and when its connections are changed from fahigher to a lower voltagesup 1y circuit, or

36 w en, from any other cause, t e motor acts 1 temporarily asagenerator; I

In the accompanying drawings, Figure 1' isa 'ew, in front elevation, ofa controller whio embodies'm'y inventiorpthe cover be? removed. Fig. 2is asectional view on line IIII .of'Fig'. 1.. Fi j3--is a sectional Fig.4is a sectional yiew on line of Fig. 3, and

, Fig. 5 is a diagrammatic view of the developl6- merit of thecontroller drum and contact fin.

as and lthe, connections thereof with the various circuits.

The controller comprises all'of the parts ordinarily embodied in acontroller for delivering multi-voltages to electric motors and forvarying the resistances of the field magcontacts 1 and stationarycontact fingers 2, the drum being operated by means of a handle.3.Mounted upon the same shaft 4 as,,55 the rotatable drum contacts, is acam wheel 5 of approximately circular form but having projections 6 and7 c )rresponding, respectively, to the-o d position of thecontroller andto the transitional period between its 60 higher and lower voltagepositions. An arm 8 1s secured, at one end, to a' short shaft 9 and, atits free end, is provided with a roller 10 which is adapted to enga ethe periphery of the cam wheel 5'. The ro ller 10 is held in engagei entwith the periphery of the cam whee 5 by means of a coil-sprin 11, oneend of which is secured to the .controIler frame 12 and the other end ofwhich is-provi-ded with a hook 13 that engages a stud 14 on the tree endof the arm 8.

A lever 15 is rigidly attached, at one end, to the rotatable shaft 9and, at its free end,'is pivoted to one end of a link 16, which, inturn,

is pivoted to a crank lever 17 of a dashpot 18. The dashpot 18 isprovided for the purpose of retarding the movement of" the freeendof thearm 8 and its roller 10 toward the cam wheel 5 after they have beenmoved outward by either of the projections 6 and 7. While any 8Qsuitable retardin means may heiemployed for this purpose, have found itconvenient to usethe dashpot shown in the drawings, which comprises acase 19 having three chambers 20, 21 and 22, a cylinder 23, a piston23*,

a link'24, a crank lever 25 and a suitable valve 26.. 1 The chambers 21and 22 are con- 1 'aerected only by a restricted passage 27 and chambers20 and 521 are connected by means of passages 28 and 2-9, the .eHec-tivecrosssection of the formerof which may be ad-=- justed fromthe outsideof the dash'pot. by means of a set-screw 30and a lock-nut'31, -while thelatter is opened and closed by means of the ball-valve26l Communication[between-the chambers 20 and 22 is controlled by the piston 23". Thed-ashpot chambers are filled'with any suitable liquid, such as Iglycerinor a mixture of glycerin and water.

If the crank lever '25, which is operated by Tneans of a shaft 32 thatconnectsthe outside of the daishpot with the corresponding crank lever'17; is moved in .the direction of the arnet circuits thereof, suchass-rotatable drum .row33, (Fig, 3), its' movement is retarded,

because'the ball-valve 26 is forced to its seat by the pressure of theliquid, and the only "opening between the chambers 20 and 21 is throughthe restricted passage 28, and the degree of this retardation dependsupon the area of this passageway, which may be adjusted,:as beforestated, by means of the setscrew 30. However, if the crank lever 25moves in the opposite direction, the pressure of the liquid in thechamber 21 raises the ball-valve 26 and the piston 23 is allowed toreturn to theposition shown in Fig. 3 without retardation.

Secured to the rotatable shaft 9, is a contact finger 35 which engageswith the drum ring 36 except when the portion 6 or the portion 7 of thecam wheel 5 engages the roller 10.

Referring now to Fig. 5, it is seen that, when the finger 35 engages thedrum ring 36, the circuit through the armature 37 of the ,motor is, forpositions from a, to f of the controller drum, from the supply conductor38,

through fingers 39, drum contacts 40 and 36,.

contact finger 35, motor armature 37, contact finger 41, drum contacts42 and 43, c.on-'

tact finger 44, blow-out coil 45, to the line conductor 46, the lineconductors being supplied from any suitable source 47 of multivoltages,such as that described in Patent No. 513,006, granted to Michael vonDolivo- Dobrowolsky January 16, 1894. If, however, the contact finger 35does not en age the drum ring 36, the circuit is from the ins conductor38, through the contact finger 39, drum contacts 40 and 36, contactfinger 48, resistance 49, armature 37 contact finger41, drum contacts 42and 43, contact finger 44, blow-out coil 45, to the line conductor 46.As before stated, the content finger 35 is raised out of engagement withthe drum ring 36 in passing from the off to the a or a position of thecontroller drum and also in passing from the f to the 9 position and iseld out of engagement therewith during a period of time the length ofwhich is determined by the adjustment of the dashpot.

If, when. the controller occupies the position g, or one of thesucceeding positions, and the motor operates at a speed corresponding tosuch position, the controller is returned to the position f, or one ofthe preceding positions, the voltage generated by theimotor ditionsprevail when the controller is moved may be in excess of that of theconductors to which the armature is connected. All injury 't'o' 'themotor or other parts, however, is prevented because the resistance 49 isinserted in the armature circuit when the controller is moved from theposition 9 to the position It will be understood that the circuits oft.e motor, when operating temporarily as a generator, are the. same asfor motor operation upon the lower voltage circuit; Similar confromposition a to position a, and vice versa.

In the 9 position of the controller drum, if the contact finger 35engages the drum ring 3.6, the circuit through the motor armature 37 isfrom the line conductor 50, through the contact finger 51, drum contacts52 and 36, contact finger 35, motor armature 37, contact finger 41, drumcontacts 53 and 54, contact finger 44, blow-out coil 45, to the lineconductor 46; but if the finger 35 does not engage the drum ring 36, thepreventive resistance 49 is inserted in the motor armature circuit,since that circuit is from the line conductor 50, through the contactfinger 51, drum contacts 52 and 36, contact finger 48, resistance 49,motor armature 37, contact finger 41, drum contacts 53 and 54, contactfinger 44 and blow-out coil 45, to the line conductor 46.

The spirally disposed sets of drum contacts 55 and thecooperatingcontact fingers 56 are employed for the purpose of varying the amount ofthe resistance 57 that is invention as utilized only when changing fromthe off to running positions of the controller, or when changingthe-voltage supplied to the motor armature, it is to be understood thatit may be. employed equally well, if desired, in connection with singlevoltage systems and may be caused to operate between any two desiredpositions of the controller. It may also be employed in the operation oftwo or more electric motors which are arranged to be connected in seriesand parallel, when changing from the paral' lel to the series connectionthereof.

I claim as my invention:

1. The combination with an electric motor having a shunt fie d magnetwinding, of a re sistance, means for connecting the same in series withthe motor-armature whenever the motor operates temporarilyas agenerator, means for short-clrcuiting the resist.-

ance and retarding mechanism for the shortcircuiting means.

2. A retarding device comprising a mem her having two chambers andcommunicat 3. A retarding device comprising a memher having two chambersand communicating passages between the chambers, a piston In testimonywhereof, I have hereunto adapted to operate in said member and tosubscribed my name this 5th day of March, open and close one of thecommunicating 1904.

passages,-a balivalve seated over another of THOMAS S. PERKINS. 5 thepassages, and means wherebythe efiect- Witnesses:

ive area of the remaining passage may be H. L. VAN VALKEN-BURG,

adjusted exterior to the member. BIRNEY HINES.

